Exit pupil

The exit pupil is the size of the opening through which the light passes and is transferred to your own pupil. On average, your pupil varies in size from 2 to 7 mm. If the exit pupil is bigger than your pupil, it is easy to see an image. If the exit pupil is smaller, it becomes much more difficult to get a good image. To calculate the exit pupil value, divide the lens size by the magnification factor.

Exit pupil = size of the lens / magnification factor

Do you want to use binoculars at night? When purchasing your binoculars, keep in mind that your pupil opens up to a maximum of 5 to 7 mm in dark situations. For night vision equipment, it is important to know that the exit pupil is at least as big as the human pupil in low light. For example, a 7x50 binoculars would be suitable with an exit pupil of more than 7 mm, which is bigger than the human pupil.

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